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## The second CFTR mutation was not detected by the testing obtained The patient shows clinical signs and symptoms consistent with cystic fibrosis (CF), including recurrent respiratory tract infections, sinusitis, pancreatitis, and salty sweat. Genetic testing reveals a G551D mutation in one allele...

## The second CFTR mutation was not detected by the testing obtained The patient shows clinical signs and symptoms consistent with cystic fibrosis (CF), including recurrent respiratory tract infections, sinusitis, pancreatitis, and salty sweat. Genetic testing reveals a G551D mutation in one allele of the CFTR gene. CF usually occurs when both CFTR alleles are mutated. Since only one mutation was found, this could indicate that the second mutation was not detected by the 36-mutation panel used. This is the best explanation for the patient's clinical phenotype. This means there might be another mutation in the CFTR gene that was not identified. **Step by step:** 1. **Patient symptoms:** * Recurrent respiratory tract infections * Sinusitis * Pancreatitis * Salty sweat 2. **These symptoms are consistent with cystic fibrosis** 3. **Genetic test:** * Shows a G551D mutation in one CFTR gene allele * Two mutated alleles are usually needed for CF 4. **Problem:** * Only one mutation was found * The patient has typical CF symptoms 5. **Possible explanation:** * There may be a second mutation. * The test only checked 36 known mutations. * The second mutation may not have been detected. 6. **Conclusion:** * The second CFTR mutation was not detected by the testing obtained.